Giles Kent was the leader of a plot to take down Ramón Salamander. He had formerly been Deputy Security Leader for North Africa and Europe in the World Zone Authority, but had been discredited and ruined by Salamander when he got too close to exposing the madman; Kent found himself framed for corruption. A number of Authority figures he spoke to wound up dead, however.
In 2018, he had a base near to Salamander's Australian facility, Astrid Ferrier as his second-in-command, and the Central European Controller, Alexander Denes, willing to listen. When he saw the Second Doctor's resemblance to Salamander, he persuaded the Doctor to impersonate Salamander and assassinate him. Kent not just pushed the Doctor into this, he forced him into his first impersonation by tipping off an alleged agent of Salamander.
Kent had actually been Salamander's ally back in 2013 and was the one who brought Salamander's scientists to the underground complex, and had simply fallen out of favour with the demagogue. He secretly planned take over Salamander's operations. The Doctor, however, had always suspected him because of his ease with murder.
After the Doctor exposed him, he retreated into the tunnels. It was here that he encountered Salamander, who betrayed Kent by shooting and wounding him. Staggering into the explosives area, Salamander pursued him and was about to finish him off, when Kent pulled the main lever, triggering the explosives. His final words were, "Well, if I'm gonna die Salamander — you'll die with me!" (TV: The Enemy of the World)